A sensor element of this kind and a method for manufacturing the sensor element are described in published German patent document DE 198 17 012, which sensor element has, between a first and a second solid electrolyte film, an annular diffusion barrier that is surrounded by an annular measured gas space. Disposed in the measured gas space are electrodes to which a measured gas, located outside the sensor element, can travel via a gas entry opening installed in the first solid electrolyte film, and through the diffusion barrier.
Also known are sensor elements in which gas entry occurs through openings disposed in the layer plane between the first and the second solid electrolyte film.
In order to compensate for production-related fluctuations in the diffusion resistance of the diffusion barrier, the diameter of the gas entry hole and thus the inside diameter of the diffusion barrier are modified in controlled fashion. For this purpose, firstly a sensor element is sintered from a charge, and the so-called limit current (pumping current) of this sensor element is ascertained; the desired inside diameter of the diffusion barrier is ascertained on the basis of the measurement result, and the ascertained inside diameter is adjusted, by drilling, for the further sensor elements deriving from the same charge.
It is disadvantageous in this context that the method for ascertaining the limit current on the sintered sensor element, and the subsequent adaptation of the inside diameter of the diffusion barrier and the gas entry opening, are time-consuming and cost-intensive. It is additionally disadvantageous that even after the above-described correction of production-related fluctuations in the diffusion resistance, the limit current can vary because the magnitude of the diffusion barrier can be subject to a variation within a charge.